David Cameron has challenged anyone to find a country with "a prouder history, a bigger heart or greater resilience" than the UK, after Russian president Vladimir Putin reportedly described Britain as a "small island no-one listens to."

Cameron delivered the impassioned defence from the G20 summit in St Petersburg, where Putin sought to brand Britain a second-tier world power yesterday, in comments regarded as an astonishing breach of diplomatic protocol.

Cameron's retort highlighted Britain's myriad historic and cultural achievements.

"Britain is an island that has helped to clear the European continent of fascism - and was resolute in doing that throughout World War Two," he said.

"Britain is an island that helped to abolish slavery, that has invented most of the things worth inventing, including every sport currently played around the world, that still today is responsible for art, literature and music that delights the entire world.

"We are very proud of everything we do as a small island - a small island that has the sixth-largest economy, the fourth best-funded military, some of the most effective diplomats, the proudest history, one of the best records for art and literature and contribution to philosophy and world civilisation."

After the impassioned speech, Cameron remarked "I'm thinking of setting this to music."

Correcting the Russian description of Britain as an island, Cameron said: "For the people who live in Northern Ireland, I should say we are not just an island, we are a collection of islands. I don't want anyone in Shetland or Orkney to feel left out by this."

The Russian comments, attributed to Putin's spokesman Dmitry Peskov, have been denied by the Kremlin.

The UK has reportedly been sidelined at the summit after MPs in the House of Commons voted against the UK being involved in a military strike against the regime of president Bashar al-Assad, who stands accused by several governments, including that of the US, of using chemical weapons in attacks on civilians.

'Putin really is a tosser'

The Russians reject US claims, and argue that the case for military intervention in Syria ought to be put to the UN Security Council, where they and fellow Syria allies China wield a veto.

While Cameron chose to evoke the spirit of Churchill, Tory MP Henry Smith chose slightly more everday prose to decry Russia's jibe, tweeting: "Putin really is a tosser."

He later expanded: "On Twitter in a slight fit of pique I might refer to him as a tosser. But in other forums, such as the House of Commons, I would accuse him of being an absurd character.

"There is his abuse of human rights against the gay community in his own country, there is the abuse of human rights in Syria where the way he is helping and prolonging that civil war there is appalling.

"I may not use that colloquial language in other forums, but frankly it is still how I feel."

G20: Cameron on the Sidelines as Obama and Hollande Talk Syria [VIDEO]